Acquired apraxia of speech (AOS) is a neurologic speech disorder that is typically caused by stroke. AOS is characterized by slow rate of speech, difficulties in sound production, and disrupted prosody. Severity can range from minor distortions in speech production to a complete loss of the ability to speak and may significantly interfere with communication. AOS is usually accompanied by aphasia and may be the primary or secondary diagnosis for approximately 24% of patients with communication disorders resulting from stroke (Duffy, 2007). Although numerous treatments have been demonstrated to result in improvements in AOS symptoms, there has been a paucity of research devoted to the development and optimization of particular treatments. Treatment intensity is potentially an important aspect of speech/language rehabilitation that has begun to receive increased attention in the field of communication disorders (Warren, Fey, & Yoder, 2007). A growing neurorehabilitative literature has provided principles of experience-dependent neuroplasticity, including the principle that intensity matters (Kleim & Jones, 2008); more intense treatment may be preferable for inducing neural plasticity. In contrast, numerous investigations across various motor learning and cognitive domains have found distributed/less-intense practice to be superior to massed/more-intense practice in promoting learning (Donovan & Radosevich, 1999; Janiszewski, Noel, & Sawyer, 2003; Lee & Genovese, 1988). Only one investigation has addressed treatment intensity in AOS (Wambaugh, Nessler, Cameron, & Mauszycki, 2013). In a pilot investigation of treatment intensity and schedule of practice, intense treatment was found to result in similar outcomes as less intense treatment for four speakers with chronic AOS and aphasia. However, several methodological issues with the pilot investigation (e.g., limited number of treatment sessions, confounding with practice schedule) necessitate further investigation with additional participants. The purpose of the proposed research is to further examine the effects of treatment intensity on outcomes associated with an established treatment for acquired apraxia of speech (AOS). Intensity, in the form of dose frequency and total intervention duration, will be evaluated with Sound Production Treatment (SPT; Wambaugh, 2004; Wambaugh, Kalinyak-Fliszar, West, & Doyle, 1998;; Wambaugh & Mauszycki, 2010; Wambaugh & Nessler, 2004; Wambaugh, Nessler, Wright, & Mauszycki, in press). The proposed research is designed to investigate the effects of intense dose frequency (i.e., nine one-hour treatment sessions per week) and traditional dose frequency (i.e., three one-hour sessions per week). Total number of treatment sessions will be held constant allowing for comparison of total intervention duration (e.g., 27 sessions over 3 weeks versus 27 sessions over 9 weeks). A two-phase, group cross-over experimental design will be utilized. Thirty-six participants with chronic AOS and aphasia will be quasi-randomly assigned to one of two treatment groups - intense first or traditional first (18 per group). One group will receive SPT applied with intense dose frequency (SPT-I) followed by SPT applied with traditional dose frequency (SPT-T). The other group will receive the treatments in the reverse order (SPT-T followed by SPT-I). A two week no-treatment interval will separate the treatment phases. The outcomes of interest will address changes in trained behaviors, untrained behaviors (i.e., generalization effects), speech intelligibility, and patient- rated communicative functioning.